A Michelson interferometer is set up for microwaves.Initially the reflectors are placed so the detector reads a maximum.When one of the reflectors is moved 12 cm,the reading goes from a minimum to a maximum six times.What is the wavelength of the microwaves?
A) 0.5 cm
B) 4 cm
C) 1 cm
D) 2 cm

Question

Quizplus · Accepted Answer

When one of the reflectors is moved by 12 cm, the path difference between the two arms of the interferometer changes by 24 cm (since the wave travels twice the distance of the mirror's displacement). We know that the detector reading goes from minimum to maximum six times, which means that the path difference changes by half the wavelength each time. Therefore, the total wavelength is given by:

Wavelength = (path difference)/(number of times detector reading changes from minimum to maximum) 
            = (24 cm)/(6) 
            = 4 cm

Hence, the answer is option B).

A Michelson Interferometer Is Set Up for Microwaves